Mail processing systems, such as, for example, mailing machines, inserters and the like, often include different modules that automate the processes of producing mail pieces. The typical mail processing system includes a variety of different modules or sub-systems each of which performs a different task on the mail piece. The mail piece is conveyed downstream utilizing a transport mechanism, such as rollers or a belt, to each of the modules. Such modules could include, for example, a singulating module, i.e., separating a stack of mail pieces such that the mail pieces are conveyed one at a time along the transport path, a stripping/moistening module, i.e., stripping open the flap of an envelope, wetting and sealing the glued flap of an envelope, a weighing module, and a metering/printing module, i.e., applying evidence of postage to the mail piece. The exact configuration of the mail processing system is, of course, particular to the needs of the user.
The stripping/moistening module includes a stripping blade for separating a flap of a moving envelope away from the envelope's body to enable the moistening and sealing process to occur. The stripping blade becomes inserted between the flap of the envelope and the body of the envelope as the envelope traverses the transport deck of the mailing machine. Alternatively, in some devices, envelopes are stacked and fed into the system with their envelopes already opened. Regardless, with the flap opened, the moistening device moistens the glue line on the flap in preparation for sealing the envelope. One type of moistening system, known as a contact moistening system, generally deposits a moistening fluid, such as, for example, water or water with a biocide, onto the glue line on a flap of an envelope by contacting the glue line with a wetted applicator.
A conventional moistening system may include an applicator, typically formed from a contact media such as a brush, foam or felt. The applicator is supplied with moistening fluid, either through physical contact with a wick, a portion of which is located in a reservoir containing the moistening fluid, or via a pump system and tubing. As an envelope is transported with its flap open, the inside of the envelope flap, where the glue line for sealing the flap is located, contacts the applicator, such that the applicator transfers moistening fluid to the flap to activate the glue. The flap is then closed and sealed, such as, for example, by passing the closed envelope through a nip of a sealer roller to compress the envelope and flap together, and the envelope is passed to the next module for continued processing.
There are problems, however, with conventional moistening modules as described above. For example, efficient sealing of the envelope flap is dependent upon the envelope flap receiving sufficient moistening fluid transferred from the applicator to the glue line on the envelope flap. If the glue line on the envelope flap does not receive sufficient moistening fluid, the glue will not activate and the flap will not seal.
On the other hand, if there is too much moistening fluid in the applicator, then the applicator will drip, and there must be some means for dealing with the excess liquid. Excess liquid can overflow and make a mess, and it can result in the supply of moistening fluid running out prematurely. In order to address these issues in the past, one technique has been for operators to use trial and error to adjust a valve to modify the flow of liquid to the applicator.
Another potential issue is uneven distribution of liquid from the applicator. Sometimes one part of the applicator may be more wet than another, resulting in uneven moistening of the envelope flap, potentially causing the sealing operation to be unsuccessful, or for excessive dripping from the region of the applicator that gets too much liquid.